Bioequivalence and Bioavailability Forum

Dear Helmut, dear All,

❝ Little is published about NCA of t_lag, except in Cawello (2003),

Meanwhile I came into touch with the lag time (first in my long, long career in BE studies) in a food BE study for one of the "(in)famous" ...prazoles.

Searching again the literature / I-net I found the following paper I'm not noticed so long (not so new if one sees the publication year ):

Czismadia F and L Endrényi
Model-independent estimation of lag-times with first-order absorption and disposition
J Pharm Sci 87, 608–12 (1998)

It contains a comprehensive description of methods for NCA estimation of t_lag. Interesting enough no one which defines the time of the first conc. >LLOQ.

After a first look their new (for me) method - named t_E, with weighted regression of values between first time with conc. >LLOQ and t_max - seems promising. Although their premises in deriving this method seems a little bit restricting ("first-order absorption and disposition", no one knows really about this).

What do you think?

What should be done with this parameter? Reporting the values only (with summary statistics) or any statistical analysis of differences between formulations under study? Which statistical method, model?
There are questions upon questions .